Quite frankly I wouldn't bother. I just imported my content/routes from 2010 to 2012, only to fing that, when opened in 2012, the imported routes had large chunks of content apparently missing - their places marked only by white, hatched double lines. Virtually all Maglev content was absent, along with several types of track (especially double track), roads, lanes, road & lane intersections, scenery items and buildings - most of it stuff that was built-in to 2010.
Updating these "absent" items (where updates were available) made no difference, so I am now faced with removing all these markers, and replacing them with suitable available content - and then re-doing the signalling, speed limits etc.
Yet another unhappy bunny on the N3V check list!